Cannot answer your specific question but suspect that given you have this MS condition that it will be one of the focus items that CBSA will consider for processing your landing. You may find that CBSA may not process your landing until you are moving on a permenant basis but you will need to check with both CBSA and IRCC.
Current guidelines due to COVID in any case specifically only recommend arriving in Canada if moving permenantly although as quoted on the forum people have argued their case at a land border, not always successfully though and having a MS condition may be one of those no way to predict
If you do manage to land successfully then probably advisable to follow the reporting requirement contacting a health authority given not doing so may cause issues later once IRCC and a health authority reconcile your status.